Metal vapor discharge tube using metal and semi-metal compounds in a discharge tube

ABSTRACT

A metal vapor discharge tube device including a discharge tube and means for introducing a metal or semi-metal into the discharge tube without auxiliary heating. The metal or semi-metal is introduced as a compound of a metal or semi-metal and a nonmetallic radical having a vapor pressure greater than one torr at the temperature of the discharge tube (which for most discharge tubes can be as high as about 300* C). The discharge in the tube causes the decomposition of the compound, thereby releasing the metal or semi-metal into the discharge for excitation. If desired, the excitation can produce lasing and the device may be used as a metal vapor laser.

United States Patent 1191 Zarowin METAL VAPOR DISCHARGE TUBE USING METALAND SEMI-METAL COMPOUNDS IN A DISCHARGE TUBE Charles B. Zarowin,Tarrytown, N.Y.

Inventor:

International Business Machines Corporation, Armonk, N.Y.

Filed: Sept. 25, 1970 Appl. No.: 75,589

Assignee:

References Cited UNITED STATES PATENTS Walter .33 1/945 Moeller PatelFried] ..331/94.5

OTH ER PU BLIC ATIONS Fraford, High Peak Power Pulsed l0p,CO Laser"12/28/65, pg. 384-385, Physics Letters, Vol. 20, No. 4.

Carfare, Continuous Operation of a Long Lived CO Laser Tube, 3/68, pg.102103, IEEE JQE.

Primary Examiner-Benjamin A. Borchelt Assistant Examiner-N. MoskowitzAttorney-Hanifin and Jancin and John J. Goodwin [57] ABSTRACT A metalvapor discharge tube device including a discharge tube and means forintroducing a metal or semi-metal into the discharge tube withoutauxiliary heating. The metal or semi-metal is introduced as a compoundof a metal or semi'metal and a non-metallic radical having a vaporpressure greater than one torr at the temperature of the discharge tube(which for most discharge tubes can be as high as about 300 C). Thedischarge in the tube causes the decomposition of the compound, therebyreleasing the metal or semi-metal into the discharge for excitation. Ifdesired, the excitation can produce lasing and the device may be used asa metal vapor laser.

3 Claims, 1 Drawing Figure POWER SOURCE ,PATENYEDMRIISIQYS 3'720'877POWER SOURCE INVENTOR CHARLES H. ZAROWIN BY 8 HM ATTORNEY METAL VAPORDISCHARGE TUBE USING METAL AND SEMI-METAL COMPOUNDS IN A DISCHARGE TUBEBACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention is in the metal vapor discharge tube and laser technology.

2. Prior Art Metal vapor lasers are known in the prior art wherein puremetal vapor is introduced into the discharge tube by auxiliary heatingof the metal. The present invention isdistinct over the prior art inthat a metal or semimetal compound is introduced into the discharge tubein a gaseous state without auxiliary heating as a consequence of thehigh vapor pressure of the compound compared to the pure metal orsemi-metal. In the discharge tube, the compound decomposes into themetal or semi-metal and the non-metallic radical. The metal is thus madeavailable for use in the discharge tube. The present invention thereforepermits the use of high melting point metals or semi-metals in adischarge tube whereas in the prior art the use of such metals orsemi-metals was impossible or impractical due to the extreme heatrequired.

SUMMARY OF THE INVENTION An object of the present invention is toprovide a metal vapor discharge tube using metals and semimetals havingrelatively high melting points.

Another object of the present invention is to provide a metal vapordischarge tube using metals or semimetals without auxiliary heatingthrough the use of metal or semi-metal compounds having vapor pressuresgreater than one torr at temperatures up to about 300C.

A further object of the present invention is to provide a system andmethod wherein metal or semi-metal compounds are introduced into adischarge tube in the vapor state without auxiliary heating wherein thecompound decomposes into metal and the nonmetallic radical.

Still another object of the present invention is to provide a metalvapor laser wherein metals or semi-metals are introduced into adischarge tube as vapor compounds.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of a preferred embodiment of the invention, as illustratedin the accompanying drawing. 1

The drawing is a schematic illustration of an embodiment of a metalvapor discharge tube according to the principles of the presentinvention.

Metal vapor lasers are useful devices that have advantages over othertype lasers such as rare gas lasers. Since electrons are not as tightlybound to metal atoms as to non-metallic atoms, a laser employing a metalvapor in the active medium can be brought into the excited state usinglower energy levels than that required for other type lasers.Heretofore, a pure metal' in a solid state was placed in a dischargetube and heated in order to convert some fraction of it into the vaporstate in the tube. There are a large number of metals having meltingpoints that are too high to provide sufficient vapor pressure in adischarge tube at practical temperatures. For example, Molybdenum (Mo)has a melting point of 2,620 C, Ruthenium (Ru) is l,950 C, Osmium (Os)is 2,500 C and Tungsten (W) is 3,030". Thus, only the low melting pointmetals which have sufficient vapor pressure at low temperature can beused in metal vapor lasers. The present invention provides a way inwhich metals such as molybdenum, ruthenium, osmium, tungsten and otherhigh melting point metals and semi-metals can be employed in the vaporstate in metal vapor discharge tubes or lasers without auxiliaryheating.

In the present invention the metal or semi-metal is introduced into thedischarge tube as a compound having a vapor pressure greater thanapproximately one torr at the temperature of the discharge tube (as highas about 300C). Thus at this temperature or above, some of the compoundis in the vapor or gaseous state. In the discharge tube the dischargeprovides energy which causes decomposition of the compound and therebyprovides the atomic species of the metal available for excitation.

MOre particularly, consider a compound composed of a metal or semi-metalM and a non-metallic radical X, the compound being represented by MX,,.In the discharge the following reaction occurs:

The reaction is reversible which means the metal or semi-metal and thenon-metallic radical will recombine in the tube to form the compound.Thus, there will be a constant decomposition and recombination processoccurring in the discharge tube so that metal or semimetal moleculeswill be available in sufficient concentration for excitation at alltimes. The excitation and consequent relaxation of the metal orsemi-metal atoms produce the emission oflight (lasing).

Referring to the drawing, a schematic representation of a discharge tubeis shown. The tube 10 may include reflectors I2 and 14 at the Brewsterangle so that emitted light may be coupled out of the tube. Conventionalvapor traps l6 and 18 may also be included to maintain the vapor in thedesired region. The tube initially contains a rare gas, for exampleargon, krypton, helium, etc. Electrodes 20 and 22 and power source 32are provided to excite the gas to provide an electrical discharge. Theelectrode regions may also be isolated by vapor traps 24 and 26. Thedischarge tube shown in the drawing is only representative, the presentinvention may be practiced with other known discharge tubes, for exampleelectrodless tubes which employ capacitive or inductive excitation.

A compound of a metal or semi-metal and a nonmetallic radical iscontained in vessel 28 which is connected to tube 10 through a valve 30.The compound in vessel 28 has a vapor pressure greater thanapproximately one torr at the temperature of the discharge tube(approximately 300C) so that the compound will be in the vapor state asa result of the heat produced by the discharge. when valve 30 is opened,the compound will enter discharge tube 10 and the discharge will causeexcitation of the compound (and in the case of some compounds, causeionization) which will cause decomposition. That is, the hot electronsin the discharge collide with the molecules of the compound and causedecomposition. After decomposition the metal molecules and thenon-metallic radical molecules will recombine upon collision, however,the discharge will continue to cause decomposition and a state ofequilibrium will be reached and there will be a concentration of metalvapor which will be excited into the lasing condition.

It was previously stated that the compounds that are employed in thepresent invention are those consisting of a metal or semi-metal and anon-metallic radical having a vapor pressure greater than torr at theoperating temperature of the discharge tube which can be as high asabout 300C.

Examples of some compounds which may be employed in the presentinvention are listed below.

Name Formula Aluminum bromide AlBr Aluminum chloride AlCl Aluminumiodide All Antimony tribromide SbBr Antimony trichloride SbCl Antimonypentachloride SbCl Antimony triiodide Sbl; Antimony pentiodide SblArsenic tribromide AsBr Arsenic trichloride AsCl Arsenic pental'luoridcAsF Arsenic hydride (arsinc) AsII; Arsenic trioxide A5 0, Berylliumborohydride BeB,H, Beryllium bromide BeBr Beryllium chloride BeClBeryllium iodide Bel Borine carbonyl BH CO Boron tribromide BBr Borontrichloride BCI Boron trifluoride BF Dihydrodiborane B H Diboranehydrobromide B BrH Triborine triamine B l-l N Tetrahydrotetraborane 8 HTetrahydropentaborane 8 H Dihydrodecaborane B H Bromine pentafluorideBrF Carbon tetrachloride CC] 4 Carbon tetrafluoride CF Carbon dioxide COCarbon suboxide C -,O Carbon disulfide CS Carbon subsulfide C 5 Carbonselenosulfide CSSe Carbon monoxide CO Carbonyl chloride COCI, Carbonylselenide COSe Carbonyl sulfide COS Chromium carbonyl Cr(CO) Chromylchloride Cr0,Cl, Ferric chloride FeCl, Gallium trichloride GaCl,Germanium hydride GeH, Germanium bromide GeBr, Germanium chloride GeCl,Trichlorogermanc GeHCl Tetramethylgermanium Ge(CH Digermane Gc,H,Trigermane Ge H Iodine pental'luoride IF Iodine heptafluoride IF, Ironpentaearhonyl Fe(C), Mercuric bromide HgBr, Mcreuric chloride HgClMercurie iodide Hgl, Molybdenum hexafluoride MoF Nickel carbonyl Ni(CO)Phosphorous tribromide PBr, Phosphorous trichloride PCl Phosphorouspentachloride PCI Phosphorous thiobromide PSBr Phosphorous thiochloridePSCI Selenium dioxide Se0, Selenium hexafluoride SeF Seleniumoxychloride SeOCl Selenium tetrachloride SeCl, Silicon tetrafluorideSiF; Bromosilane siH Br Chlorosilane SIH CI Fluorosilane SiH Flodosilane SiH l Bromodichlorol'luorosilane SiBrChFChlorotrifluorosilane SiC 1 F; Dihromochlorol'luorosilane SiBr ClFDibromosilane V siH Br Dichlorodifluorosilane SiCl F, Difluorosilane SiHF, Disilane Si H Disiloxane (SiH;),0 Fluorotrichlorosilane SiCl FHexachlorodisilane SI CI Hexafluorodisilane Si F Octachlorotrisilane SiCI Tetrasilane SiJ'l Tribromofluorosilane SiBr F Tribromosilane SiHBrTrichlorosilane SiI-ICl Trifluorosilane SiHF Trisilane Si H Disilazane(SIHQ N Sulfur hexafluoride SP Sulfur dioxide S0 Sulfur monochloride SCl Sulfur trioxide (or) SO; Sulfur trioxide (B) SO; Sulfur trioxide (7)S0 Thionyl bromide SOBr- Thionyl chloride SOCl Tantalum pentafluorideTaF Tellurium tetrachloride TeCl, Tellurium hexafluoride TeF Titaniumtetrachloride TiCl Tungsten hexafluoride WF; Uranium hexafluoride UFVanadyl trichloride \(OCI; Zirconium tetrabromidc ZrBr; Zirconiumtetrachloride ZrCl, Zirconium tetraciodide ZrI The above list isrepresentative of compounds having vapor pressure greater thanapproximately one torr at 300C. A person having ordinary skill in theart could look up other compounds using a chemical handbook. A veryextensive list is provided by Daniel R. Stull in Industrial andEngineering Chemistry, 39,517 (1947).

What has been described is a metal vapor laser wherein metals with veryhigh melting points can be employed whereas heretofore the use of suchmetals was impractical or impossible.

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that the foregoing and other changes in formand details may be made therein without departing from the spirit andscope of the invention.

What is claimed is:' l. A metal vapor discharge tube device comprising:a discharge tube containing a gas, means for exciting said gas in saidtube to produce an electrical discharge in said tube, said electricaldischarge causing said discharge tube to operate at a given temperature,and

means for introducing a compound of a metal or semi-metal and anon-metallic radical into said tube in the vapor state, said compoundhaving a vapor pressure greater than one torr at the operatingtemperature of said discharge tube during said discharge, wherein saidelectrical discharge decomposes said metal or semi-metal compound intothe metal or semi-metal and the non-metallic radical followed byelectron excitation of the metal to produce population inversion,wherein said decomposition occurs without external heating but is due tothe operating temperature of the discharge tube.

2. A metal vapor discharge tube device according to claim 1 wherein saidgas and said metal or semi-metal 5 6 in said discharge tube is excitedby said excitation as a vapor,said compound having a vapor pressuremeans to produce stimulated emission oflight. greater than one torr atthe operating temperature 3. A method for introducing a metal orsemi-metal of said discharge tube during said discharge, into adischarge tube containing a gas comprising th wherein said electricaldischarge causes said comte of; 5 pound to decompose into the metal orsemi-metal producing an electrical discharge in said gas in said and then-m ta lic radical and prduces elecdischarge tube, said electricaldischarge causing P elicitation offhe metal to pr duc population saiddischarge tube to have an operating temperalnf'erslonv wherem 531ddecomposltlon occurs ture, and without external heating but is due tothe operatintroducing a compound of a metal or semi-metal mg temparaturconhc dlschal'ge tubeand a non-metallic radical into said discharge tube

1. A metal vapor discharge tube device comprising: a discharge tubecontaining a gas, means for exciting said gas in said tube to produce anelectrical discharge in said tube, said electrical discharge causingsaid discharge tube to operate at a given temperature, and means forintroducing a compound of a metal or semi-metal and a non-metallicradical into said tube in the vapor state, said compound having a vaporpressure greater than one torr at the operating temperature of saiddischarge tube during said discharge, wherein said electrical dischargedecomposes said metal or semi-metal compound into the metal orsemi-metal and the non-metallic radical followed by electron excitationof the metal to produce population inversion, wherein said decompositionoccurs without external heating but is due to the operating temperatureof the discharge tube.
 2. A metal vapor discharge tube device accordingto claim 1 wherein said gas and said metal or semi-metal in saiddischarge tube is excited by said excitation means to produce stimulatedemission of light.